Stop the SDK's own trimmer version deciding whether CI can restore

CI went red across the whole repository — main's run 125 and every open pull
request at once — on a restore that never reached a compiler:

    error NU1004: The package reference Microsoft.NET.ILLink.Tasks version has
    changed from [10.0.10, ) to [10.0.11, ). The packages lock file is
    inconsistent with the project dependencies so restore can't be run in
    locked mode.

Nothing in any of those commits touched a package. .NET had shipped SDK 10.0.400.

◆ THE VERSION IN THE LOCK FILES WAS NEVER THIS REPOSITORY'S TO DECIDE.

Microsoft.NET.ILLink.Tasks is referenced by nothing here. The SDK adds it to any
project setting IsTrimmable or IsAotCompatible — DodoSSH.Contracts and
DodoSSH.Crypto do, and the Android head gets it from trimming being on by
default — and it supplies the version itself, from the KnownILLinkPack item in
its own Microsoft.NETCoreSdk.BundledVersions.props. 10.0.302 says 10.0.10;
10.0.400 says 10.0.11.

packages.lock.json records that as a Direct reference with a requested range, so
what the committed file actually means is "whichever SDK last ran a restore".
global.json says rollForward: latestMinor, so setup-dotnet installs the newest
10.x SDK that exists on the morning it runs. The gate did its job — an unreviewed
dependency change is exactly what it is there to stop — but the change it caught
was not one anybody could have reviewed, and it will recur on every servicing
release.

Regenerating the lock files alone would have been the worse repair, and not only
because it holds until the next release. It cannot be done from this machine at
all: every SDK installed here tops out at 10.0.302, which writes 10.0.10 straight
back and re-breaks CI. The recorded version would flip according to who restored
last — the precise state locking exists to prevent.

So the version is pinned in Directory.Build.targets and the three lock files are
regenerated against the pin. It is an Update on the SDK's item rather than a
PackageVersion in Directory.Packages.props because the reference is implicit:
the SDK supplies a version, so central package management is never consulted. It
sits in a target because the conditioning is on %(TargetFramework) — all the
KnownILLinkPack items share one identity and only that metadata separates
net10.0's from net8.0's — and item batching in a condition is legal inside a
target and MSB4191 during evaluation.

Pinned forward to 10.0.11 rather than back to 10.0.10, which would have been a
one-line change with no lock file churn. Holding the trimmer a release behind the
framework it analyses to dodge an error is how a missed trim warning happens, and
taking the newer one makes the bump a reviewed diff, which is what the gate was
asking for.

Verified against the SDK that broke it rather than only the one here:

  - sdk:10.0-alpine, 10.0.400, `dotnet restore DodoSSH.slnx --locked-mode` —
    exit 0. That is ci.yml's line, on CI's SDK.
  - the android workload on sdk:10.0-noble, 10.0.400, locked-mode restore of
    DodoSSH.Client.Android — exit 0. That is scripts/ci-android.sh's line.
  - locally on 10.0.302, the same locked-mode restore of the solution — exit 0.

One set of lock files satisfying both SDKs is the whole point of the pin, and the
third check is the one that demonstrates it.

Release build clean: 0 errors, and 0 IL-prefixed diagnostics from the newer
analyser on the two trimmable projects. 1,869 tests over 19 suites, none failing.

A caution for the next person, learned the hard way here: `--force-evaluate` on
Windows rewrites every lock file it touches with CRLF, and 23 of the 26 had no
content change at all. Only the three that really moved are in this commit.

src/DodoSSH.Contracts/packages.lock.json

@@ -22,9 +22,9 @@
       },
       "Microsoft.NET.ILLink.Tasks": {
         "type": "Direct",
-        "requested": "[10.0.10, )",
-        "resolved": "10.0.10",
-        "contentHash": "f5VCIE7AJpd5YvzNTeMGVzQIgyE9tX+AreTYwQF+REbu+DZo/2Ae+jNSwhPEYrVz6RRkd7y8ubXjk6Nn6Ka+Cg=="
+        "requested": "[10.0.11, )",
+        "resolved": "10.0.11",
+        "contentHash": "IBf7lbovvjGWVWXZX5cJ/cO0WXbId0Zq4BuSeT94mGZuOAP66oMeH9PTBZ9Jpp3Jb6jtK0qm/NyUbPRo1gC/wQ=="
       },
       "MinVer": {
         "type": "Direct",